Hydraulic fuel injection apparatus



April 3, 1934. s. R. HUNTER HYDRAULIC FUEL iNJECTION APPARATUS Filed Sept. 29, 1950 IN VEN TOR.

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Patented Apr. 3, 11%34 lli'irflRAULllC ENJIEGTHON APPARATUS Samuel Rsllilunter, Sterling, fill. Application September 29, 1930, Serial No. M55369 i ll claim. (or. 299- lii'ikz) My invention has reference to a hydraulic fuel injection apparatus. of the type used for the feed of liquid fuel in some types of motors, as for instance what is commonly known as the Diesel engine. In the injection of fuel in engines of the class named it is desired to have the fuel leave the nozzle of the injector in the form of a fine spray or mist, and to have the successive charges of a uniform and regular character. The present invention is specially designed for such purpose, and to eliminate unfavorable actions to be found in the injecting devices now in use. Some of these are leakage of the fuel, irregular action and chattering of the valve, and delivery of the fuel to the combustion chamber in a small stream or otherwise than in a perfect vapor. Another result obtained by the use of the novel apparatus set forth herein is to greatly increase the efiiciency of the operation, and correspondingly reduce the fuel consumption and cost of operating.

I'he action of the device is entirely automatic, the injection of the fuel being under the control of a needle-valve, and a secondary valve member being provided which is operated by the force of the fuel admitted to the injector, which secondary valve member has an initial movement of its own before actuating the needle-valve. This secondary valve member is under a normal extensile force, which force is increased or built up during the initial movement of said member, to

assist in the return movement thereof. This return movement is effective in causing the injection of a charge of fuel into the combustion chamber, as will be hereinafter more fully set forth.

The above named, and other features and advantages of the invention will more fully appear from the following specification, taken in connection with the accompanying drawing, which shows the invention in medial longitudinal section.

The reference number 1 indicates a cylindrical body member, or housing, having a central bore 2, enlarged into a chamber 3, and with a further enlargement 4, threaded to receive the similarly threaded end 5 of a hollow plug 6, closing the larger or rear end of the housing. Slidable in the .bore 2 is a tubular: piston 7, provided at its inner end with a head 8, against which bears one endof an extensile coiled spring 9, the other end of which bears against a shoulder 10 on the interior of a plug 11, which also has a threaded engagement with the end 4 of the housing.

Slidably mounted in the bore of the piston 7 is r a. needle-valve 12, the pointed end of which bears normally against a plug 13 in the small end of the housing. and closes an aperture 14 in said plug. The valve 12 is projected into a rod 15, on which is fixed a collar 16, between which and the end of the piston is interposed a coiled spring 17. A similar spring 18 is positioned between the opposite side of said collar and a collar 19, in which the rear end of the rod 15 is slidably supported. The outer end of the collar 19 bears against the inner end of a plug 20, which has a threaded engagement with the outer end 21 of the plug 11, said plug being fitted with a head 22, suitable for wrench connections. The springs 17 and 18 have a balancing effect on the piston, tending to promote free movement thereof in either direction. The tension of the spring 18 is the stronger, however, with the result that the needle-valve is held normally in a closed position.

At the outer end of the needle-valve i2 is a collar 23, and in the path of movement of the piston 7 outwardly, the purpose of which will be more fully hereinafter pointed out.

The bore of the small end of the housing 1 is also threaded at 24, to receive a similarly threaded plug 25, provided with a small perforation 26. The plug 25 is hollow, and houses a nozzle 27, having a central opening forming a passage for fuel between the opening 14 and perforation 26. Said perforation provides a vent for the injection of successive charges of the fuel into the combustion chamber, which is not shown in the drawing.

At one side of the housing 1 is a pipe connection 29, from the opening in which a channel 30 leads to a space 31 at the end of the piston 7. Upon a supply of liquid fuel being admitted to said channel under pressure from a suitable source of supply the force thereof exerted upon the end ofthe piston 7 will cause said piston to move rearwardly, until the rear end ofsaid piston comes in contact with the collar 23, whereupon the continued movement of the piston causes the rear end thereof to come in contact with the collar 23 and move the needle-valve 12 in the same direction, opening the passage to the nozzle and discharge vent. The particular construction of the nozzle apparatus is not considered to be novel in itself, and changes can be made in the form and arrangement thereof without interfering with the effectiveness of the injector.

l The plug 20 is fitted with a threaded bore in which is held a similarly threaded set-screw 32, provided with a lock-nut 33. The inner end 01' the set-screw 32 is in proximity to the end of the stem 15 and limits the rearward movement of the needle-valve 12. By adjustment of said setscrew the degree of opening of the needle-valve may be controlled, and the feed capacity increased or diminished as desired.

The force of the spring 9 is sufficient to hold the piston '7 in a normally inactive position, as shown in the drawing, but in the rearward movement of said piston additional power is stored in said spring. It will be understood that the operation of the injector is of an intermittent character, in which the pulsatory actions follow each other in rapid succession, the impetus therefor being furnished by a pump or other compressive force, providing the injection apparatus with a supply of fuel under pressure, amounting to several hundred pounds to the square inch. This force is applied for an instant, sufficiently long to enable the piston to perform its work. Im mediately following the opening of the valve 12 the compressive force is cut off,and the tension of the spring 9 operates to force the piston '7 back into its original position, driving before it and out through the opening 14 the fuel charge. The successive injections are thereby produced by the positive and uniform action of the piston, instead of being dependent upon the compressive force .of the fuel supply, with its irregular and spasmodic action. This action of the piston results in the'increased efliciency and other salutary results hereinbefore mentioned.

After the piston engages with the needle-valve the additional movement to open said valve may be very slight, but in the initial movement of the piston there is a sufficient storage of energy in the spring 9 to insure a prompt and forceful re- .turn movement of the piston. It will be observed that the return of the piston is entirely independent of the needle-valve, which follows the same in quick sequence in closing the vent.

In the initial movement of the piston '7 the space 31 at the end of the piston is increased, by the recession of the piston in the bore 2, and the amount of the fuel charge to be injected into the combustion chamber is correspondingly increased.

What I claim, and desire to secure by Letters Patent, is:

A hydraulic feed injection apparatus, comprising a cylindrical casing of larger and smaller diameters, having a relatively small bore in its smaller end, a larger central bore, and a still larger space in its larger end, the last-named space having an internal thread, a hollow plug having a. thread engageable with said first-named thread to close the large end of said casing, a plug closing the small end of said casing and provided with a discharge vent, a piston slidable in said smaller'bore and spaced from saidv lastnamed plug at its outer end, a fuel passage leading to said space, a spring holding said piston yieldably in normal position, a needle-valve slidable in said piston and holding said discharge vent normally closed, said valve being adapted to be opened by said piston at the end of a predetermined movement thereof, and said needlevalve having a rod'extension centrally of said spring, a spring abutment on said rod, and springs upon said rod within said first-named spring bearing against said abutment, one of said last-named springs tending to assist in opening said needle-valve, and the other one tending to close said valveythe last-named spring being the stronger of the two.

SAMUEL R. HUNTER. 

